This invention relates in general to an improved tubing hanger, and in particular to an improved landing adapter for providing a soft landing for a tubing hanger in the bore of a tree or wellhead housing.
Designs for landing tubing hangers in casing hangers for wells in the ocean floor are well known in the prior art. A tubing hanger typically carries or suspends one or more strings of tubing which extend down into the subsea well. Many different tubing hanger designs exist and are the subject of numerous prior art patents. Some of the earlier versions of tubing hangers required a running tool employing a dart for operation that restricted the bore of the tubing hanger. Other designs provide a running tool allowing full bore tubing access during running, while providing means for controlling downhole safety valves during both running and landing operations.
For example, in U.S. Pat. No. 4,067,062, the tubing hanger is lowered into the well and releasably secured to the casing hanger by hydraulic manipulation of the running tool after the tubing hanger has been oriented in the casing hanger. After further hydraulic manipulation, the running tool may be released from the hydraulic set tubing hanger and later run back into the well and reconnected to the tubing hanger for retrieval. Although each of these designs are workable, it is difficult to avoid xe2x80x9chardxe2x80x9d landing and possibly damaging the tubing hanger in the well due to the depths at which the subsea wells are typically located. Thus, an improved design for xe2x80x9csoftxe2x80x9d landing a tubing hanger in a wellhead is needed.
In one embodiment of the present invention, a tubing hanger with a landing adapter is installed in the bore of a production tree. The landing adapter is permanently mounted on the lower end of the tubing hanger to softly land the tubing hanger. The landing adapter acts as a buffer between the conventional landing shoulder in the bore and a shoulder on the tubing hanger. The landing adapter makes the initial contact with the bore so that the tubing hanger does not have to absorb the harsh impact.
The landing adapter comprises a hydraulically-actuated sleeve that strokes axially relative to the tubing hanger. Initially, the sleeve is extended and locked when it is run into the well so that the landing adapter can be hard-landed in the bore. When the sleeve lands in the bore, the impact is absorbed by the landing adapter buffer, not by the tubing hanger. After the hanger with the landing adapter has landed in the bore, hydraulic fluid is bled off so that the tubing hanger gradually descends axially relative to the sleeve and the tree to the retracted position. The landing adapter buffer remains in the tree and is not retrieved after the tubing hanger is landed in the bore.